Trucks may utilize tandem axles where the axles are connected together by an inter-axle drive shaft. The forward tandem axle has parallel axis input and output shafts with the input on the upper shaft centerline, a helical gear drop to the forward axle pinion and a parallel output on the upper centerline to the rear axle. The forward tandem axle chassis mounting must optimize the transmission to forward tandem axle drive shaft universal joint angles. The inter-axle drive shaft is then a compromise for the universal joint operating angles resultant from the front/rear axle side view installation angles. The typical tandem hypoid rear axle gear set has lower efficiency as compared to a spiral bevel gear set. The tandem rear axle can utilize spiral bevel gears to improve the inter-axle drive shaft joint angles and efficiency but the joint angles cannot be completely optimized. Alternatively, the tandem rear axle can be a negative offset hypoid to achieve the best inter-axle shaft joint angles but this arrangement necessitates several rear axle negative hypoid primary gear set performance deficiencies. The above summarized compromises associated with tandem axles typically results in poor noise, harshness and vibration in the driveline as well as decreased durability.